Photoluminescence Line‐Shape Analysis of Highly n‐Type Doped Zincblende GaN

Abstract

An investigation of different n‐type doped zincblende gallium nitride thin films measured by photoluminescence from 7 K to room temperature is presented. The spectra change with increasing free‐carrier concentration due to many‐body effects such as the Burstein–Moss shift and band‐gap renormalization. The samples are grown by molecular beam epitaxy on a 3C‐SiC/Si (001) substrate, and a free‐carrier concentration above 1020 cm−3 is achieved by introducing germanium as a donor. The analysis of the measured spectra by a line‐shape fit yields different transition processes for different doping concentrations and temperatures, such as a band–band transition and a band–acceptor transition. The conduction band dispersion of Kane's model is perfectly suited to explain the experimental data quantitatively.